Tarpaulin cover systems are used for selectively covering and uncovering objects. A common use is in connection with open top beds, particularly vehicles beds such as truck bodies. One advantageous form of mechanism for moving the tarpaulin selectively to its uncovering condition is through the use of a cable system wherein the cable is mounted to a pulley at each end of the bed with a crank connected to one pulley to cause the cable to move in either a forward or a reverse direction. The tarpaulin is provided with a plurality of spaced bows which would extend over the top of the bed. The cable is mounted to the bows. The lead most bow is secured to the cable so as to cause the lead most bow to move in conjunction with the movement of the cable. Thus, the cable movement can cause the bows to be pushed together with the tarpaulin being in an accordion type fashion for uncovering or exposing the top of the vehicle of the bed. Alternatively, by pulling forward on the lead most bow, the remaining bows follow and the bed is covered. This basic system is described in U.S. Pat. No. 4,189,178 which issued to Nello Cramaro.
A variation of the above basic system includes the provision of a mechanism associated with the lead end of the tarpaulin for selectively elevating the lead end of the tarpaulin. As a result, when the tarpaulin is moved to its covering or uncovering condition at least a portion of the tarpaulin is elevated above the top of the bed. Once in its final covered or uncovered condition the lead end is lowered to contact or go over the top edge of the bed.
It would be desirable to provide a transmission assembly for selectively elevating the lead end of the tarpaulin during its movement and then lowering the lead end in a simple and convenient manner.